Saying “there is no difference” between Syrian Kurdish forces and Islamic State of Iraq and Levant (ISIL), Turkish President Recep Tayyip Erdogan on May 29 condemned U.S. assistance in the Kurds’ offensive on ISIL’s Syrian stronghold.

“The support they give to… the YPG (militia)… I condemn it,” said Erdogan.

“Those who are our friends, who are with us in NATO… cannot, must not send their soldiers to Syria wearing YPG insignia,” Erdogan said.

Ankara views the YPG as a terrorist group and has accused it of carrying out attacks inside Turkey and being the Syrian branch of the Kurdistan Workers’ Party (PKK) which has fought an insurgency against the Turkish state for over three decades.

“The PKK, the PYD, the YPG, Daesh (ISIL), there is no difference. They are all terrorists,” Erdogan said.

The PKK is on the U.S. list of foreign terrorist organizations but regards the YPG as a useful ally in the fight against ISIL. U.S. military officials say they will continue to work with the YPG, which provides the bulk of the so-called Syrian Democratic Forces (SDF).

About 200 U.S. special forces are in northern Syria helping the SDF target ISIL’s de facto capital Raqqa and guiding in coalition air strikes.

Erdogan said on May 29 that Turkey will continue to carry out military operations against the PKK.

“Haven’t they destroyed our mosques? These people are atheists… They do not act according to our values,” he said, promising to “see through to the end” the fight against PKK.